Trammel head



July 5, 1949. G. E. ROEDDING TRAMMEL HEAD Filed March 9, 1946 Patented July 5, 1949 UNITED STATES PATENT OFFICE TRAMMEL HEAD Gordon E. Roedding, Anderson, Ind.

Application March 9, 1946, Serial No. 653,327

4 Claims.

This invention relates to that type of draftsmans instrument known as a beam compass.

The main object of the invention is to simplify the adjustment of a pencil or pen along the beam to change its radius. A further object is to provide an adjustment of the pencil along the beam by mere manual pressure on the pencil assembly to move it in the direction desired. A still further object is to accomplish the above mentioned objects by mechanism which shall be efficient, simple and comparatively inexpensive. Other objects and advantages will be understood from the description which follows.

In the accompanying drawing:

Fig. 1 is a view in elevation of a part of a beam carrying the improved pencil assembly, certain parts being broken away and in section.

Fig. 2 is a section on line 2-2 of Fig. 1.

Fig. 3 is a section on line 3-3 of Fig. 1.

Fig. 4 shows a group of three parts in perspective, the parts being in disassembled relation.

Referring by reference characters to the drawing, numeral 5 is applied to the beam of a beam compass. The beam is to be provided with a convenient or conventional pivot which is not a part of this invention and is not shown.

The pen or pencil, the spindle of which is marked 'I, must be moved along the beam to adjust its radial distance from the pivot axis of the beam. In many such instruments, the adjustments require the release of a set screw and a resetting thereof after a sliding adjustment has been made.

In this improved device the spindle of the pencil passes through registering openings 9, II, I3 in the three parts I5, I1 and I9 which constitute an assembly. This assembly is so constructed that it has a gripping lock on the beam at any position of adjustment, said adjustment being done by manual eiort.

The spindle end is staked to part I5 around opening 9. Part I5 has arms 33 to slidably engage the beam. It has tongues 35 which locate it relative to the second part I l. Part I1 is a spring clamp having a base 25 and divergent arms 2l slotted at 21. The upper ends of these arms are bent to form adjacent ends 29, the bend being marked 3I. In the final assembly the beam passes through slots 21 and the upper ends of the slots grip the beam. The tongues 35 of part I5 extend through slot 21' beneath the beam and thereby maintain the parts I5 and I1 in their xed relative position. Part I9 carries the before mentioned parts I5 and I1 with the spindle 1. It has side walls 2I and is open at the top. Its end walls 23 are divided and consist of halves each bent from a side Wall and having a space 23 between their adjacent ends for the passage of the beam. The end walls do not reach the base and they thereby leave a space through which projects the tongues 35 of part I5. Also the upper region of the side walls 2I are cut away so that the bent ends of clamp arms 2'I may be accessible to manual pressure by an operator. The spindle has a flange 3l which together with the staking of part I5 to said spindle securely holds said assembly of parts together.

It will be seen that arms 2'I hold the assembly on the beam and that the upper ends of the slots afford a positioning grip. Manual pressure on either arm 2'I and subsequent pressure will relieve the grip and will push the assembly since the grip of each arm is in eiect a one way clutch. Obviously both arms may be simultaneously pressed by thumb and finger and the assembly moved in either direction.

I claim:

1. In a beam compass, a beam, a carrier having divided end walls for the passage of said beam, a clamp mounted on said carrier Iand having diverging slotted arms for the passage of the beam therethrough, the ends of said slots adapted to releasably grip said beam, and a spindle holder mounted on said clamp and having arms engaging the slotted arms of said clamp.

2. In a beam compass, a beam, a marker spindle, means to adjust said spindle along said beam including an assembly of parts connected together and to said spindle, a first, one of said parts having resilient arms provided with slots, the ends of which support said assembly on the beam and which arms releasably grip the beam to maintain the assembly in adjusted position, and a second of said parts being staked to said spindle and having tongues projected through said first part.

3. The invention defined by claim 2, with said spindle having a ange and said assembly including a third part Iadapted to support said rlrst and second parts, said three parts supported on said flange, and said third part having end Wall slots for the passage of said beam.

4. In a beam compass, a beam, a marker spindle, means to adjust said spindle along said beam including an assembly of parts connected together and to said spindle, a rst one of said parts having resilient arms provided with slots the ends of which releasably grip the beam to maintain the assembly in adjusted position, and a second of said parts having tongues projected through said rst part.

GORDON E. ROEDDING.

REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 447,642 Hausdorfer Mar. 3, 1891 953,464 Heller et al Mar. 29, 1910 998,616 Jewell et al July 25, 1911 1,007,424 Bjorklund Oct. 31, 1911 

